For seven-and-a-half years, maternity photographer Keri Vaca has been photographing poverty-stricken women in the Homeless Prenatal Program free of charge. Why? Because most of them haven't had a chance to celebrate their pregnancies.

"My goal is for them to have fun for the 10-15 minutes I am with them and forget their troubles and just focus on feeling good and celebrated," Vaca, who visits the program once a month, tells Life & Style. "I love showing them a photo from the back of the camera and seeing their face light up."

Small Miracles Photography/Keri Vaca

The nonprofit program, based in San Francisco, helps women struggling with issues ranging from homelessness to domestic violence, and their stories often stick with Vaca.

"I have had a few that were in their last weeks of pregnancy and the baby's dad had walked out on them," she shares.

Small Miracles Photography/Keri Vaca

"I had a mom who didn't have a bra on because someone in the shelter accidentally took hers. She was embarrassed and sad," Vaca recalls. "I couldn't imagine being pregnant in a temporary shelter where you pack your things each day and don't know what tomorrow will bring."

Small Miracles Photography/Keri Vaca

Ultimately, the photographer hopes her images encourage people not to judge. "We are all more alike than different and this could be me, this could be you…You have no idea how these women ended up where they did," Vaca explains to Life & Style.

"What you need to know is they are worthy of love and support. They are trying to change their path and Homeless Prenatal Program is that beacon of hope they need. I want the moms to feel strong and beautiful."

To see more of Vaca's photographs, check out her website. And for more information on the Homeless Prenatal Program, go here.